1. Field of the Invention
This invention relates generally to shrimping nets and other equipment designed for shrimp trawling in the open sea. More specifically, it describes an improved Turtle Exclusion Device ("TED") or TED section for inclusion in a trawling net designed to capture shrimp.
2. Description of Prior Art
According to current practice, shrimp trawling nets consist of very large forward portions which taper (as one moves away from the vessel towing the net) to a comparatively narrow opening. At this opening there is affixed a comparatively narrow cylindrical section of net (generally referred to as the "cod," "bag" or "sock") which is open at its forward end to receive the catch funnelled into it by the forward portion of the net, and closed at its opposite end to trap marine life that enters. Turtle exclusion devices are generally disposed at the juncture of the forward portion of the net and the opening to the "cod." Alternatively, they may be in a generally cylindrical section of net included at this juncture for the purpose of holding portions of the turtle exclusion device in proper spaced relation to themselves and other portions of the shrimp trawling nets.
Representative examples of prior art in this area may be seen in U.S. Pat. Nos. 3,015,903; 3,440,752; 4,043,068; 4,402,154; 4,739,574; 4,805,335; and 4,869,010. U.S. Patent No. 3,015,903 issued to H. P. Willingham in 1962 illustrates several possible changes over prior art in the area of shrimp trawling nets and equipment. However, the portion of said patent most relevant to the innovations discussed herein are related to FIG. 7 which is described as a "novel trash rejection construction incorporated in the net bag." This "construction" features a rectangular bottom frame across which is suspended a piece of canvas having a longitudinal slit. An inclined grate having curved vertical bars is positioned over the bottom frame with its upper edge forward of its lower edge. As the net and grate move through the water, objects too large to move through the bars are forced downward toward the canvas suspended across the bottom frame and, according to the inventor, are eliminated from the net by effecting a passage through the slit in said canvas.
The use of an inclined grate having parallel bars or members to force objects too large to pass through away from and out of the opening to the cod or bag of the net is very common and is seen in one form or another in many of the other patents reviewed. It is also common for said grate to be placed with its members or bars parallel to the direction in which the rejected material is to be forced. Thus, where rejected material is to be directed upward or downward, the parallel members forming the grate are vertical. Likewise, if rejected material is to be forced to the side, the parallel members forming the grate are horizontal.
More complex examples of the art in this area are seen in the Trawl Net System patented by J. H. Minter in 1969 (U.S. Pat. No. 3,440,752) and the methods and apparatus for classifying marine items patented by Pence in 1983 (U.S. Pat. No. 4,402,154). The Trawl Net System, includes, among its other features, a "junction box" provided with a grate allowing certain types of sea life passing through to be captured. Undesired marine life forms purportedly pass through a resilient gate or are ejected from the junction box by a wiper engaging the grill. The Pence patent describes a box like mechanism for separating marine life having a side-to-side grate inclined toward one side. A flexible barrier is positioned on the side to which larger items are directed, allowing same to escape from the net.
More in keeping with the current art in this area are, however, the Turtle Excluder Device (U.S. Pat. No. 4,739,574) and the Apparatus for Exclusion of Debris from Bottom Trawls patented by Saunders (U.S. Pat. No. 4,869,010). The Turtle Exclusion Device patented by Saunders features an inclined vertical grate with its leading edge at the bottom and with a hinged turtle escape door at the top of the assembly. The apparatus described in U.S. Pat. No. 4,869,010 is basically identical to the Turtle Exclusion Device previously described except that it is disposed so that its vertical grate is inclined with its leading edge at the top and with its hinged gate located at the bottom. Examples of current art in this area may also be found at 50 C.F.R. .sctn.227.72 which describes "qualified turtle excluder devices."